<script setup>
import { userLoginService } from '@/api/user.js'
import { User, Lock } from '@element-plus/icons-vue'
import { ref, onMounted } from 'vue'
import { useUserStore } from '@/stores'
import { useRouter } from 'vue-router'
const form = ref()

// 整个的用于提交的form数据对象
const formModel = ref({
  username: '',
  password: '',
  verifyCode: ''
})
// 整个表单的校验规则
// 1. 非空校验 required: true      message消息提示，  trigger触发校验的时机 blur change
// 2. 长度校验 min:xx, max: xx
// 3. 正则校验 pattern: 正则规则    \S 非空字符
// 4. 自定义校验 => 自己写逻辑校验 (校验函数)
//    validator: (rule, value, callback)
//    (1) rule  当前校验规则相关的信息
//    (2) value 所校验的表单元素目前的表单值
//    (3) callback 无论成功还是失败，都需要 callback 回调
//        - callback() 校验成功
//        - callback(new Error(错误信息)) 校验失败

const validateVerification = (rule, value, callback) => {
  if (value === '') {
    callback(new Error('请输入验证码'))
  } else {
    callback()
  }
}
const rules = {
  username: [
    { required: true, message: '请输入用户名', trigger: 'blur' },
    { min: 5, max: 10, message: '用户名必须是 5-10位 的字符', trigger: 'blur' }
  ],
  password: [
    { required: true, message: '请输入密码', trigger: 'blur' },
    {
      pattern: /^\S{6,15}$/,
      message: '密码必须是 6-15位 的非空字符',
      trigger: 'blur'
    }
  ],
  verifyCode: [{ validator: validateVerification, trigger: 'blur' }]
}


onMounted(() => {
  resetCode();
});

let captchaCanvas = ref(null);
let generatedCode = '';
const resetCode = () => {
  const canvas = captchaCanvas.value;
  if (!canvas) return;

  const ctx = canvas.getContext('2d');
  if (!ctx) return;

  // Generate a new four-digit code
  generatedCode = '';
  for (let i = 0; i < 4; i++) {
    generatedCode += Math.floor(Math.random() * 10);
  }

  // Clear the canvas
  ctx.clearRect(0, 0, canvas.width, canvas.height);

  // Draw background noise
  for (let i = 0; i < 500; i++) {  // Increase the number of noise points
    // Set the color to a random RGB color
    ctx.fillStyle = `rgb(${Math.random() * 256}, ${Math.random() * 256}, ${Math.random() * 256})`;

    // Draw a small rectangle at a random position with a random size between 1 and 3
    ctx.fillRect(Math.random() * canvas.width, Math.random() * canvas.height, Math.random() * 2 + 1, Math.random() * 2 + 1);
  }

  // Set a margin for the characters
  const margin = 30;  // adjust this value to change the spacing between characters

  // Calculate the width of each character area
  const charAreaWidth = (canvas.width - 2 * margin) / generatedCode.length;

  // Draw each character of the code
  for (let i = 0; i < generatedCode.length; i++) {
    const char = generatedCode[i];

    // Set the color to a random RGB color
    ctx.fillStyle = `rgb(${Math.random() * 256}, ${Math.random() * 256}, ${Math.random() * 256})`;

    // Set the font to a size between 20 and 40
    ctx.font = `${20 + Math.random() * 20}px Arial`;

    // Set the text align to center
    ctx.textAlign = 'center';
    ctx.textBaseline = 'middle';

    // Set a larger random scale and skew
    ctx.setTransform(1, Math.random() * 0.2 - 0.1, Math.random() * 0.2 - 0.1, 1, 0, 0);

    // Calculate the position of the character with a random offset
    const x = margin + i * charAreaWidth + charAreaWidth / 2 + (Math.random() - 0.5) * charAreaWidth * 0.3;
    const y = canvas.height / 2 + (Math.random() - 0.5) * canvas.height * 0.3;

    // Draw the text at a position based on the canvas width, the code length, and the margin
    ctx.fillText(char, x, y);

    // Reset the transform
    ctx.setTransform(1, 0, 0, 1, 0, 0);
  }
};


const userStore = useUserStore()
const router = useRouter()
const login = async () => {
  await form.value.validate()
  const res = await userLoginService(formModel.value)
  userStore.setToken(res.data.token)
  ElMessage.success('登录成功')
  router.push('/')
}

</script>

<template>
  <!-- 
    1. 结构相关
      el-row表示一行，一行分成24份 
       el-col表示列  
       (1) :span="12"  代表在一行中，占12份 (50%)
       (2) :span="6"   表示在一行中，占6份  (25%)
       (3) :offset="3" 代表在一行中，左侧margin份数

       el-form 整个表单组件
       el-form-item 表单的一行 （一个表单域）
       el-input 表单元素（输入框）
    2. 校验相关
       (1) el-form => :model="ruleForm"      绑定的整个form的数据对象 { xxx, xxx, xxx }
       (2) el-form => :rules="rules"         绑定的整个rules规则对象  { xxx, xxx, xxx }
       (3) 表单元素 => v-model="ruleForm.xxx" 给表单元素，绑定form的子属性
       (4) el-form-item => prop配置生效的是哪个校验规则 (和rules中的字段要对应)
  -->
  <el-row class="login-page">
    <el-col :span="12" class="bg"></el-col>
    <el-col :span="6" :offset="3" class="form">
      <!-- 登录相关表单 -->
      <el-form :model="formModel" :rules="rules" ref="form" size="large" autocomplete="off">
        <el-form-item>
          <h1>登录</h1>
        </el-form-item>
        <el-form-item prop="username">
          <el-input v-model="formModel.username" :prefix-icon="User" placeholder="请输入用户名"></el-input>
        </el-form-item>
        <el-form-item prop="password">
          <el-input v-model="formModel.password" name="password" :prefix-icon="Lock" type="password"
            placeholder="请输入密码"></el-input>
        </el-form-item>

        <el-form-item label="验证码：" prop="verifyCode">
          <el-input style="width: 150px;" v-model="formModel.verifyCode" placeholder="请输入验证码" maxlength="4" clearable />
          <canvas ref="captchaCanvas" @click="resetCode" style="translate: -60px 15px;"></canvas>
        </el-form-item>

        <el-form-item class="flex">
          <div class="flex">
            <el-checkbox>记住我</el-checkbox>
            <el-link type="primary" :underline="false">忘记密码？</el-link>
          </div>
        </el-form-item>
        <el-form-item>
          <el-button @click="login" class="button" type="primary" auto-insert-space>登录</el-button>
        </el-form-item>



        <el-form-item class="flex">
          <el-link type="info" :underline="false" @click="router.push('/register')">
            注册 →
          </el-link>
        </el-form-item>
      </el-form>
    </el-col>
  </el-row>
</template>

<style lang="scss" scoped>
.login-page {
  height: 100vh;
  background-color: #fff;

  .bg {
    // background: url('@/assets/logo2.png') no-repeat 60% center / 240px auto,
    //   url('@/assets/logo3.png') no-repeat center / cover;
    background: url('@/assets/logo4.jpg') no-repeat center / cover;
    border-radius: 0 20px 20px 0;
  }

  .form {
    display: flex;
    flex-direction: column;
    justify-content: center;
    user-select: none;

    .title {
      margin: 0 auto;
    }

    .button {
      width: 100%;
    }

    .flex {
      width: 100%;
      display: flex;
      justify-content: space-between;
    }
  }
}
</style>
